1. Field of the Invention
The present invention generally relates to a suspension assembly used for supporting a hard disk drive's head. More particularly, it relates to a head suspension assembly for a hard disk drive using a flexible circuit board (FCB).
2. Description of the Related Art
Due to the rapid development of powerful computer systems and the advent of the information age, the demand for high-capacity and high-density computer storage media has increased. Accordingly, various research and development have been devoted to the fabrication of computer storage media with superior recording density characteristics.
In addition, to improve the data processing speed, techniques of either increasing the number of rotation of a hard disk drive or manufacturing its actuator of light weight have been proposed. Besides, considering a signal-to-noise ratio in the manufacture of hard disk drives becomes of great importance in order to provide high-capacity random-access storage and high recording density.
A hard disk drive having a base 9, and a cover 10, as shown in FIG. 1, serves as an auxiliary computer storage media, and includes a magnetic disk 2 that rotates by a spindle motor 1, a magnetic head, or transducer, 5 which reads, records, or erases data on the magnetic disk, a metallic suspension assembly 6 which supports head 5 from an access mechanism, or actuator body, 4 which positions the read/write head onto the required track of magnetic disk 2 by pivoting on a pivot 3, an electronic control circuit 7 which controls the above components, and an electrical interface 8 which connects the drive with a host computer system.
The following description relates to the operation of the hard disk drive. Once power is applied to the hard disk drive, the spindle motor rotates at predetermined speeds. As the spindle motor rotates, the magnetic disk also turns. Subsequently, when the disk rotates at high speeds, the magnetic head flies to a predetermined height, and is positioned to the required track of the magnetic disk. The hard disk drive sends a ready-to-read/write/erase signal into the host computer system.
When the reading/writing information is input to the hard disk drive under the above condition, the access mechanism pivots about its vertical axis in response to a position/speed signal output from the electronic control circuit, and the read/write head of the access mechanism moves to the required track of the magnetic disk. The read/write head performs the read/write operation by a read/write circuit. The position and speed of the head are controlled by the control circuit during the read/write operation.
The magnetic head, one of the most important components of the hard disk drive, is mounted on the access mechanism, i.e., actuator body, by means of a head suspension assembly which serves as a spring.
FIGS. 2 and 3 each depict a conventional head suspension assembly. FIG. 2 shows a side view of the conventional head suspension assembly, and FIG. 3 is a perspective view of the same.
Referring to FIGS. 2 and 3, a metallic suspension assembly 20 is designed to be in substantially triangular shape by using a thin metallic plate. The suspension assembly 20 includes a base plate 23 which is fixed to an actuator body 22, a load beam portion 24 which serves as a spring, and a flexible structure 25 (flexure) that is fixed onto a front end of the load beam portion 24 by welding and to which a head 21 is attached. A boss 26 and a swaging hole 27 are formed on a base plate 23. Actuator body 22 has a swaging tooling hole 28. Load beam portion 24 has flanges 30 bent at right angles on both sides except a region where a resilient portion 29 is formed
When fixing suspension assembly 20 to actuator body 22, boss 26 of suspension assembly 20 is first inserted into swaging tooling hole 28 of actuator body 22. As a steel ball (not illustrated) of larger diameter than the diameter of swaging hole 27 is forced through swaging hole 27, boss 26 expands horizontally whereby suspension assembly 20 is fixed to actuator body 22. A magnetic wire (not illustrated) is connected to an output terminal of head 21 by laser welding. The wire is connected to a terminal of a flexible circuit board (not illustrated) by soldering, wherein the terminal of the flexible circuit board is then connected to an input terminal of a pre-amplifier (not illustrated).
According to the above-described technique, the head suspension assembly is fixed to the actuator body by a ball swaging process. Problems that occur due to the mechanical damage during the ball swaging process effect the head performance. In addition, because of the noise created by connecting the head output terminal and the pre-amplifier input terminal with the magnetic wire by laser welding and soldering, and the wire's resistance, it is difficult to obtain a high signal-to-noise ratio.
FIG. 4 is another conventional head suspension assembly. To obtain a high signal-to-noise ratio, according to this conventional head suspension assembly, a flexible circuit board 41 is bonded to a load beam portion 44 of a metallic suspension assembly 40, so that flexible circuit board 41 is directly connected to a head.
In the magnetic head of the above head suspension assembly of FIG. 4, there are four lead wires from the head's output terminal (not shown) corresponding to pad 1, pad 2, pad 3 and pad 4, and the flexible circuit board is bonded to the suspension assembly instead of using the lead wires. The above-described head suspension assembly may prevent a decrease of the signal-to-noise ratio by the direct connection of the head and flexible circuit board but still has a problem of deterioration to the head performance by the ball swaging process used to bond the suspension assembly to the actuator body. Particularly, in case of a contact-type head/media, the required gram load force is several tens or several hundreds of milligrams (mg), so there is a risk of spoiling the design of the suspension assembly employing the ball swaging process.